Cellular communication systems can be based on a variety of different cellular standards employing Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and combinations of FDMA and TDMA. These cellular communication systems use frequency modulation to transmit speech and data information on a variety of different radio channel frequencies. The channel spacing between the different radio channel frequencies used in a cellular communication system varies depending on the cellular standard employed. Wideband cellular standards such as IS-95 and GSM require wide channel spacing to receive wideband frequency- modulated signals ("wideband signals"), while narrowband cellular standards such as NAMPS and the IS-54 standard require a narrower channel spacing to receive narrowband frequency-modulated signals ("narrowband signals").
Prior art cellular radios having dual-mode receivers have been designed to operate in cellular communication systems employing either a narrowband standard or a wideband standard, for example, IS-95 dual-mode phones, or the dual-mode satellite/cellular phone described in U.S. patent application Ser. No. 08/305,780, filed Sep. 14, 1994, and entitled "Dual-Mode Frequency Synthesizer for Satellite/Cellular Phones," which is incorporated herein by reference. These prior art dual-mode receivers are capable of demodulating both wideband signals and narrowband signals. In order to demodulate both wideband signals and narrowband signals, the dual-mode receivers of the prior art use duplicate receiver components. For example, prior art dual-mode receivers use a wideband filter apparatus to filter the received wideband signals and a different narrowband filter apparatus to filter the narrowband signals. The duplication of receiver components in a dual-mode receiver increases the size and cost of the cellular radio. A dual-mode receiver is needed that reduces the duplication required to demodulate both wideband and narrowband signals.